Occlusive arterial disease is commonly treated by bypassing the occluded vessel. The most successful treatment is achieved through the use of autogenous vein grafts. However, when vein is not available, synthetic grafts made of such materials as expanded polytetrafluoroethylene or polyethyleneterephthalate are substituted.
The surgical application or small caliber synthetic vascular grafts for medium or small vessel bypass is limited by frequent graft occlusion due to the thrombogenic nature of currently available graft materials. In small vessel grafts, blood flow is reduced and there is a rapid adsorption and accumulation of blood proteins on the graft surface. Shortly after implantation in a patient, the luminal aspect of a prosthetic vascular graft heals by the formation of a surface of fibrin referred to as the pseudointima. Thrombin binds to this fibrin pseudointima, where it can contribute to platelet activation and the formation of platelet rich thrombi. Bound thrombin may also contribute to further fibrin accretion that in turn leads to distal embolism.
The seeding of vascular grafts with endothelial cells has been proposed as a solution to the problem of thrombogenicity (reviewed by Mosquera and Goldman, Br. J. Surg. 78: 656-660, 1991). Although endothelial seeding of grafts has shown beneficial results in experimental settings, the technology has not progessed to the point that seeded grafts suitable for routine use can be produced.
There is a clear need in the art for biologically compatible, synthetic materials having reduced thrombogenicity. Such materials should be resistant to the deposition of blood proteins and to platelet adherence. These materials would be useful as vascular grafts, synthetic heart valves, artificial organs and in any prosthetic application where the material will be exposed to blood and a potential for thrombogenesis exists. The present invention provides such materials and methods for preparing the materials. Materials prepared in accordance with the methods of the present invention are also useful as experimental models in the study of thrombogenic and fibrinolytic processes.